Fathers earn almost a fifth more than men who do not have children, according to research.

The ‘fatherhood pay bonus’ means that the salaries of men who have children before they are aged 40 are likely to be 19 per cent more than childless colleagues.

Potential explanations for the 'fatherhood pay bonus' rise are that the incentive of being breadwinner for a family pushed them to work harder, that employers rewarded their perceived increased loyalty or that men tend to wait until they have a decent wage to have children.

'Female employment soared in the 1980s, since the mid-1990s girls have been outperforming boys at school at university, and in the last decade the gender pay gap between men and women in their 20s has almost disappeared.

Motherhood penalty: Women with children are paid more than a quarter less than fathers of the same age

'But discussions about gender and pay are often divorced from the wider structural context that drives female disadvantage in work and wages, which is closely associated with their primary responsibility for care, particularly childcare.

'Our analysis of the earnings of women born in 1958 and 1970 suggests that the impact of having children on women's earning and employment prospects has, on average, improved slightly over time.

'Most of the mothers of children born in 1958 would have taken a long break from work after having children, and those in relatively good jobs experienced a fall in occupational status and earnings.

'Their daughters were more likely to return to work quicker, and to maintain occupational status after having children.

'Full-time working women born 12 years later, in 1970, are doing better but mothers are still penalised compared both to women without children and to men with children.

'But we were surprised to find a 'fatherhood pay bonus'. With dads in the UK tending to work long hours and many fathers still seeing themselves as breadwinners, they may be working longer to make up for their partners working fewer hours.'

Fatherhood bonus: Men may be waiting until they have a decent wage before having children